Improved vaccine strategies of infectious bronchitis disease to reduce shedding of virulent virus from infected birds

Mushtaq T. B. AL-Zuhariy


Infectious bronchitis (IB) threatens the economies of entire nations, by adversely affecting the backyard farmers, poultry producers and poultry industry throughout the world. Infectious bronchitis virus (IBV), a member of the Coronaviridae family, is probably one of the most avian pathogens prevalent in the poultry industry worldwide. In the field which presents difference structures, especially in the S1 spike protein. Complicated immune response against IBV due to few similarities between serotypes. High mutation rate of the virus, in addition to the management and environmental factors, compromise the efficacy of the available vaccines and difficult the control of disease. Prepared effective IB vaccines from any IBV strain stimulates the immunity widely against morbidity and mortality after challenge with virulent IBV strains. On the other hand, vaccinates with live IBV vaccines do not reduce infection or viral shedding after challenge. In order to compare the prepared IBV vaccines taken four different IBV genotypes to determine stimulating immunity and the amount of viral shedding after challenge, two hundred fifty one day broiler chicks divided into five groups and vaccinated with oil-adjuvant vaccines prepared of Iraqi isolates (II, I-II, I- III and I-IV). different inactivated IB viruses including strains QX, CH Baghdad M 2014, CH Baghdad F1 2013, CH Babylon F2 2013, and an allantoic fluid control. Using a hemagglutination inhibition test for serum analysis after challenge with virulent IBV (Variant2) to knowledge antibody content against each of the vaccine antigens, Monitored the vaccinated birds daily for of morbidity and mortality were recorded, and used PCR to determine the amount of viral copy of examined clinical samples in selected periods of viral shedding. All vaccines used in the study gave good protection against morbidity and mortality, except the control group. Homologous vaccines gave good protection and lowest viral shedding in the trachea, kidney and feces compared to the heterogeneous vaccines.
Key word: infectious bronchitis disease, inactivated vaccines, hemagglutination inhibition, viral load, challenge.

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